# cptts2.f man page

cptts2.f

## Synopsis

### Functions/Subroutines

subroutine cptts2 (IUPLO, N, NRHS, D, E, B, LDB)
CPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

## Function/Subroutine Documentation

### subroutine cptts2 (integer IUPLO, integer N, integer NRHS, real, dimension( * ) D, complex, dimension( * ) E, complex, dimension( ldb, * ) B, integer LDB)

CPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

Purpose:

``` CPTTS2 solves a tridiagonal system of the form
A * X = B
using the factorization A = U**H*D*U or A = L*D*L**H computed by CPTTRF.
D is a diagonal matrix specified in the vector D, U (or L) is a unit
bidiagonal matrix whose superdiagonal (subdiagonal) is specified in
the vector E, and X and B are N by NRHS matrices.```
Parameters:

IUPLO

```          IUPLO is INTEGER
Specifies the form of the factorization and whether the
vector E is the superdiagonal of the upper bidiagonal factor
U or the subdiagonal of the lower bidiagonal factor L.
= 1:  A = U**H *D*U, E is the superdiagonal of U
= 0:  A = L*D*L**H, E is the subdiagonal of L```

N

```          N is INTEGER
The order of the tridiagonal matrix A.  N >= 0.```

NRHS

```          NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B.  NRHS >= 0.```

D

```          D is REAL array, dimension (N)
The n diagonal elements of the diagonal matrix D from the
factorization A = U**H *D*U or A = L*D*L**H.```

E

```          E is COMPLEX array, dimension (N-1)
If IUPLO = 1, the (n-1) superdiagonal elements of the unit
bidiagonal factor U from the factorization A = U**H*D*U.
If IUPLO = 0, the (n-1) subdiagonal elements of the unit
bidiagonal factor L from the factorization A = L*D*L**H.```

B

```          B is COMPLEX array, dimension (LDB,NRHS)
On entry, the right hand side vectors B for the system of
linear equations.
On exit, the solution vectors, X.```

LDB

```          LDB is INTEGER
The leading dimension of the array B.  LDB >= max(1,N).```
Author:

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:

June 2016

Definition at line 115 of file cptts2.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page cptts2(3) is an alias of cptts2.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK